Summit Therapeutics Announces Expansion of Ivonescimab Global Phase III Development Program with HARMONi-GI3 Study in 1L Colorectal Cancer

Summit Therapeutics Inc. (NASDAQ: SMMT) ("Summit," "we," or the "Company") today announced the expansion of its Phase III clinical development program of the novel, potential first-in-class investigational bispecific antibody, ivonescimab, into colorectal cancer (CRC) with the initiation of the global Phase III HARMONi-GI3 trial.

Summit is starting a Phase III clinical study, HARMONi-GI3, to evaluate ivonescimab plus chemotherapy compared to bevacizumab plus chemotherapy as first line therapy in patients with unresectable metastatic colorectal cancer (CRC).

Clinical trial sites for HARMONi-GI3 are planned to begin activating in the United States prior to the end of the year. The multiregional study intends to enroll approximately 600 patients. The primary endpoint for this study is progression-free survival.

Each year, approximately 48,000 patients are estimated to be diagnosed with or have unresectable recurrent metastatic MSS CRC (also known as mismatch repair-proficient colorectal cancer, or pMMR CRC).¹ There have been limited options approved in the United States in the last 20 years for those first-line patients whose tumors are not positive for certain biomarkers or other activating mutations.

MSS CRC is a setting where monoclonal PD-1 inhibitors such as pembrolizumab and nivolumab have failed to show a clinically meaningful benefit. Anti-VEGF therapy (e.g., bevacizumab) plus chemotherapy is the standard of care for many patients with 1L metastatic MSS CRC.

At the 2024 Annual Congress of the European Society of Medical Oncology (ESMO 2024), Akeso Inc. (Akeso) presented encouraging Phase II data of ivonescimab in combination with FOLFOXIRI chemotherapy demonstrating an objective response rate (ORR) of 81.8% (95% CI: 59.7% – 94.8%) and a disease control rate (DCR) of 100% (95% CI: 84.6% – 100.0%) in 22 patients. This Phase II study, AK112-206, was conducted in China and sponsored by Akeso with all relevant data exclusively generated, managed, and analyzed by Akeso. In the ivonescimab plus FOLFOXIRI chemotherapy arm, there were no treatment emergent adverse events that led to permanent discontinuation of ivonescimab as of the data cutoff from the ESMO 2024 presentation.